Study the information about the structure: preposition (in/for/about) + -ing.
1. If a preposition is followed by a verb, the verb ends in -ing.

Are you interested in working for us?

How about meeting for lunch tomorrow?

Mike must be fed up with studying.
2. Remember the use of these prepositions + -ing.

Before + -ing
After + -ing
By + -ing
Without + -ing

Before going out, she called Martin.

You can improve your Spanish by reading more.

She has many problems without having to worry about yours.